1. Field of the Invention
The present invention relates to an apparatus for editing PCM signals and, more particularly, to an apparatus having an electronic editing function to edit PCM signals with means of storing the edit-point proximate signals in memories.
2. Description of the Prior Art
In the conventional electronic PCM audio signal editing apparatus designed for additionally inserting a new PCM audio signal in another PCM audio signal obtained through pulse code modulation of an audio signal and recorded on a magnetic tape or for recording such a new PCM audio signal successively to the PCM audio signal already recorded, there are known some examples as disclosed in Japanese Patent Laid-open Nos. 55 (1980)-163672 and 57 (1982)-176577 and so forth. According to such electronic editing apparatus, the operation is performed by previously writing the edit-point proximate sample data of the PCM audio signals in a memory and then reading out the sample data of the PCM audio signals from the memory in accordance with the input data indicative of the edit point. Besides the above, as disclosed in Japanese Patent Laid-open Nos. 54 (1979)-58013 and 55 (1980)-105871, the sample data of the PCM audio signals to be edited are cross-faded at the edit point so as to obtain satisfactory reproduced sounds which are aurally continuous with smoothness.
In the above editing apparatus, an editing start point and an editing end point are determined individually in an insert editing mode by a memory rehearsal which confirms the editing state by reading out the stored sample data from the memories and monitoring the analog reproduced sound, and thereafter both the apparatus for reproducing the new PCM audio signal and the apparatus for reproducing the previously recorded PCM audio signal are driven synchronously with each other in a playback mode to actually run the tapes, and a preview is executed to monitor the reproduced sound for a relatively long time. Therefore the editing efficiency is rendered extremely low and the tapes need to be repeatedly driven to eventually bring about a problem of additional burdens on the mechanisms. In the practical editing operation, modifications with insert editing are frequently adopted posterior to an assemble editing mode, and in the actual insert editing, there are many cases of replacing musical notes or the like of several or less seconds, so that it becomes necessary to enhance the short-time insert editing efficiency.
In the electronic editing apparatus mentioned, the procedure of setting the edit point can be executed accurately by a memory rehearsal with relative simplicity, but in editing the signals with regard to fast-touch piano music or the like, it is still extremely difficult to achieve exact determination of the edit point even with such memory rehearsal. And there exists another problem that a proper grasp is impossible with regard to the cross-fade conditions of PCM audio signals at the edit point.
It is customary, in the above electronic editing apparatus, that display means is provided for displaying the operational states of the reproducing-side tape recorder and the recording-side tape recorder by the use of symbols and messages as well as for numerically displaying the present tape running position in each tape recorder, the editing start point and the editing end point with respect to the time code recorded on the tape. And in accordance with such visual representation on the display means, the editor is enabled to advance the editing procedure while confirming the operational state of each tape recorder, the present tape position and so forth therein.
Furthermore, even with the numerical display, it is impossible to exactly grasp that the sound being monitored corresponds to which of the data stored in the memories, hence raising a problem that the editing operation cannot be performed accurately with high efficiency and sufficient certainty.